Fungi May be Used to Control Fungus-farming Beetles

The redbay ambrosia beetle (Xyleborus glabratus) — native to India, Japan, Myanmar, and Taiwan — was first detected in 2002 in southeast Georgia. It was presumably introduced in wood crates and pallets, and its rapid spread has killed 6,000 avocado trees in Florida, where it was discovered in 2010.

The beetles are fungus farmers that bore holes into healthy avocado trees, bringing with them the pathogen that causes laurel wilt, a disease that threatens the $54 million-a-year avocado industry in the state of Florida. Growers have traditionally tried to control the beetles by spraying insecticides on the trees, but now University of Florida scientists may have a new solution — fungi that could be used as a biological control agent, which could help growers use less insecticide.

“When you want to manage a pest, you want an integrated pest management approach,” said Daniel Carrillo, an entomology research assistant professor at the university’s Tropical Research and Education Center in Homestead, FL. “This provides an alternative that we would use in combination with chemical control.”

He and his colleagues exposed the red ambrosia beetles to three commercially available fungi, and all of the beetles died. Then they sprayed the fungi on avocado tree trunks, and the beetles became infected while boring into the trunks. About 75 percent of those beetles died, said Carrillo.

While the the tree treatments did not completely stop female beetles from boring into the trees, the researchers say their treatment can prevent the female beetles from laying eggs, and Carrillo sees this study as the first step toward controlling the beetle in a sustainable way.

The study, which also involved scientists from the USDA Crop Bioprotection Research Unit, was published in the journal Biological Control.